This investigation is concerned with three aspects of early embryonic development in R. pipiens, and with certain aspects of the cell life cycle in general. 1. The mechanism of meiotic maturation and ovulation is being studied in terms of the interrelationships between: a) protein phosphate turnover and exchange, b) protein kinase- adenyl cyclase activity, c) cation binding to membrane phospholipids and phosphoproteins, and d) electrical and ion selectivity changes at the plasma and nuclear membranes. 2. Changes in macromolecular syntheses are being studied using cell cultures of dissociated blastula and gastrula stage embryos. Turnover, acetylation, and phosphorylation of histones are being correlated with electrical and ionic changes during the induction of tissue specific enzymes. 3. Macromolecular (RNA, DNA, and protein) synthetic events in synchronized dissociated blastula cells and human cancer cells are being correlated with changes in membrane potential and intracellular cation concentrations during the cell life cycle.